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GRAPE GRO WING bodies in dead tissue and infecting pruning wounds during winter rains. However, the infection period is wider, and these fungi can enter most any time following pruning. The overwintering stages of this disease also can be prevented with lime sulfur sprays. To avoid young vine decline, be very careful where you obtain your vines and propagation material. 5. Pierce's disease This bacterial disease tends to occur epi- sodically following warm, wet winters when there is lush growth in riparian areas where the causal agent Xylella fastidiosa builds up large amounts of cells that are then transmitted by sharp shooters feed- ing on lush green growth infecting nearby vines. Glassy-winged sharpshooters are po- tentially more harmful than native sharp- shooters, as they can infect vines by feed- ing directly on woody stems for a longer period. There are strategies to control these pests, but ultimately disease-resistant vines would be very helpful. Dr. Walker has been developing a group of hybrid vines with a resistant gene taken from native Ameri- can grapes and crossed back into standard wine varieties. Seedlings are screened with bio-techniques to be sure that the resis- tant gene is present; if so, the seedlings are placed into trials to determine if PD resis- tance is adequate and fruit quality is also suitable for fine winemaking. Walker and his lab presently are screening the latest generation of vines that are 97% vinifera. There are promising resistant selections that can be used to plant in areas prone to Pierce's disease that will be suitable for making quality wine. He also is starting a similar program to develop resistance to powdery mildew. Conclusions Long-term vineyard health is being enhanced by a modest investment in research and plant breeding that has the potential for enhancing the productive life of grapevines. The longer the vineyard lasts, the longer the initial in- vestment can be paid for. Advances in the past 10 years by hard-working scientists will make a big difference for our industry in the near future. Glenn McGourty is the UC Cooperative Extension winegrowing and plant science advisor for Lake and Mendocino counties. He is the technical editor for the "Organic Winegrowing Manual" published by the University of California Agricultural and Natural Resources division. He also tends a 1-acre vineyard of the aromatic Italian winegrape variety Arneis on his property along the Russian River near Ukiah, Calif. Scan the QR code with your smart- phone for conference details. American Society for Enology and Viticulture n a tion al conference sixtythird 63 sci en ce a platform for progress 63rd ASEV National Conference Portland Marriott Downtown Waterfront Hotel Portland, Oregon June 18–22, 2012 special events • Alternative Varieties Symposium • Merit Award Presentation – Dr. Roger Boulton, University of California, Davis • Industry Seminars • Research Reports Visit our website for registration and program information. www.asev.org 530-753-3142 JOIN NOW AND SAVE! Member pre-registration fees are up to 50% lower than non-member fees. Wines & Vines APRiL 2012 57